Inside Microsoft® SQL Server® 2008: T-SQL Querying

Iteration/Recursion

Iterative approaches apply some form of loops or recursion. Many iterative algorithms traverse graphs. Some traverse graphs a node at a time and are usually implemented with cursors, but these are typically very slow. I will focus on algorithms that traverse graphs one level at a time using a combination of iterative or recursive logic and set-based queries. Given a set of nodes U, the next level of subordinates refers to the set V, which consists of the direct subordinates (children) of the nodes in U. In my experience, implementations of iterative algorithms that traverse a graph one level at a time perform much better than the ones that traverse a graph one node at a time.

Using iterative solutions has several advantages ...